(1) Field of the Invention
The field of the present invention relates to the reliability of electronic equipment or sub-equipment in an aircraft, such as in particular an airplane or a rotorcraft. Such electronic equipment or sub-equipment may be made up of one or more electronic components such as chips, microprocessors, or electronic cards. Such pieces of electronic equipment or sub-equipment may also consist in one or more electronic components such as chips, microprocessors, or electronic cards.
(2) Description of Related Art
Such electronic equipment may suffer failures or malfunctions that are random, thus preventing any preventative action by replacement. Such electronic equipment is therefore maintained in corrective manner whenever a random failure occurs. Thus, it is essential for an aircraft manufacturer to use electronic equipment having reliability that can be predicted in worthwhile manner.
The term “predicted reliability” is used to designate reliability determined by calculation upstream from an operator of the electronic equipment by using a reliability model for predetermined functional and environmental conditions.
Thus, such predicted reliability corresponds to estimating a probability of failure by calculation as a function of certain functional conditions for a piece of electronic equipment or as a function of certain environmental conditions.
The invention thus relates more precisely to a monitoring method and system that make it possible firstly to measure environmental and functional conditions of such electronic equipment while it is in operation, and secondly to determine an expected reliability for said electronic equipment under verifiable environmental and functional conditions.
The expected reliability is thus the expected result given by a reliability model that takes functional and environmental conditions as its parameters, when that model is given the conditions actually seen by the electronic equipment as its parameters.
Furthermore, the observed reliability of a piece of electronic equipment corresponds to reliability determined on the basis of a measured operating time interval between two successive failures of a given component.
In general manner in the field of aviation, and as described in particular in the following documents: XP 027218802 (“A review of uncertainty in flight vehicle structural damage monitoring, diagnosis and control: challenges and opportunities” by I. Lopez et al.), US 2014/188405 A1, US 2008/313501 A1, and US 2008/172268 A1, it is known to determine the observed reliability of a piece of electronic equipment in order to compare it with a predicted reliability. Nevertheless, such a comparison cannot be adapted as a function of the environmental and functional conditions of such electronic equipment while it is in operation.
Consequently, with the vast majority of methods for monitoring reliability that are presently known, it is not possible to determine whether a difference between the observed reliability and the predicted reliability for a piece of electronic equipment is due, for example: to a problem in the design of the electronic equipment, or to a component in the electronic equipment, or indeed on the contrary to environmental or functional conditions of such electronic equipment while it was in operation.
Document US 2014/181595 A1 describes a method of monitoring the reliability of an SSD type storage unit. It describes using an environmental sensor for making a reliability model as a function of real usage of the storage unit.
However, in Document US 2014/181595 A1, the storage unit is not described as being electronic equipment installed in an aircraft. Furthermore, there is likewise nothing to say that reliability is determined on the basis of failure data transmitted by an operator when replacing a piece of electronic equipment.
Furthermore, that document also does not describe the particular calculation of an observed reliability obtained specifically from such failure data, followed by comparing that reliability with an expected reliability, and even less does it describe generating a warning signal if the observed reliability is less than the expected reliability as calculated, in particular as a function of variations in at least one state parameter P and as a function of a predicted reliability.